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VETERINARY SERVICES MEMORANDUM NO. 800.65

TO: Veterinary Services Leadership Team

Directors, Center for Veterinary Biologics

Biologics Licensees, Permittees, and Applicants

FROM: Jack A. Shere

Deputy Administrator

SUBJECT: Eggs and Chickens for Production of Veterinary Biological Products

I. PURPOSE

This memorandum provides guidance on preparing veterinary biological products that use 

embryonated chicken eggs or chicken tissue as an ingredient. It is meant to assist licensees, 

permittees, and applicants in meeting the purity and quality requirements in title 9, Code of 

Federal Regulations (9 CFR), part 113.50.

II. CANCELLATION

This memorandum cancels Veterinary Services Memorandum No. 800.65 dated September 

20, 2002.

III. BACKGROUND

Purity and quality requirements for ingredients of veterinary biological products are specified 

in 9 CFR 113.50. Specific ingredient requirements for each licensed product are found in the 

applicable Outline of Production or Special Outline. This memorandum defines the infectious 

agents that should be excluded from domestic specific pathogen free (SPF) eggs and 

chickens used to produce veterinary biological products without specifying the methods by 

which a source flock should be established or maintained. It also recommends procedures for 

the management and disposition of eggs and chickens after a disqualifying disease outbreak 

in a source flock. Information is also provided on interpretations of a specific test for 

reporting results on an APHIS Form 2008.

IV. PURITY AND QUALITY RECOMMENDATIONS

A. Source Flock

For the purposes of this memorandum, the term “source flock” will be defined as the 

flock maintained for the production of embryonated SPF eggs. Domestic source 

flocks shall be used to prepare products. If the embryonated eggs are hatched to 

produce SPF birds for the production of infectious bursal disease or coccidiosis 

vaccines, these birds are considered part of the source flock and should be free of any 

clinical signs of infectious disease.

United States 

Department of 

Agriculture

Animal and Plant 

Health Inspection 

Service

Veterinary Services

Washington, DC 

20250
VETERINARY SERVICES MEMORANDUM NO. 800.65

Page 2

B. Agents of Concern

The licensee or permittee should maintain records to demonstrate that each lot of 

embryonated chicken eggs or chickens used to produce veterinary biological products 

has been derived from an unvaccinated flock free of the following infectious agents, 

as demonstrated by negative serology:

1. Avian adenoviruses; groups I (serotypes 1-12), II, and III

2. Avian encephalomyelitis virus (AE)

3. Avian influenza virus (AI), type A

4. Avian reovirus (Reo)

5. Infectious bronchitis virus (IB); Massachusetts, Connecticut, Arkansas, and JMK 

strains

6. Infectious bursal disease virus (IBD)

7. Laryngotracheitis virus (LT)

8. Lymphoid leukosis virus (LL); subgroups A, B, and J

9. Marek’s disease virus (MD); serotypes 1, 2, and 3

10. Newcastle disease virus (NDV)

11. Reticuloendotheliosis virus (REV)

12. Mycoplasma gallisepticum

13. Mycoplasma synoviae

14. Salmonella gallinarum

15. Salmonella pullorum

16. Other agents deemed inappropriate by APHIS

C. Clinical Signs in a Source Flock

In the case of eggs or tissue culture derived from eggs, the licensee or permittee 

should document that the source flock is negative for lymphoid leukosis antigen 

(subgroups A, B, and J), negative for clinical signs of fowlpox, and negative on 

environmental culture for Salmonella spp. Birds used for production should be free of 

clinical signs of any infectious disease. An agent causing clinical signs or 

seroconversion in production birds is referred to as a disease agent. Disqualifying 

agents or disease agents are to be treated in a similar fashion as for disease outbreaks.

D. Source Flock Monitoring

The licensee or permittee shall describe, in a filed Outline of Production or Special 

Outline, the methods and frequency of source flock monitoring and the test methods 

used.
VETERINARY SERVICES MEMORANDUM NO. 800.65

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E. Procedures for Handling Eggs and Chickens

Once introduced into the licensed establishment, licensees and permittees should 

handle eggs and chickens for the production of veterinary biological products in a 

manner that maintains their pathogen-free status. The licensee or permittee should 

describe such handling procedures in the facility blueprint legend.

V. DISEASE OUTBREAKS

A. Notification of Disease Outbreaks

The licensee or permittee should require notification from the source flock owner 

within 24 hours of a positive test indicating the presence of a disqualifying disease or 

any disease agent causing clinical signs in a source flock (including birds used to 

produce infectious bursal disease virus and coccidia fractions). If a disqualifying 

disease or disease agent is confirmed in a source flock, the licensee or permittee shall 

notify the Center for Veterinary Biologics-Inspection and Compliance (CVB-IC) 

within 24 hours.

B. Determining the Period of Suspect Eggs and Birds

In the event of a disease outbreak in a source flock used to produce embryonated 

eggs, CVB-IC will set the date of initial seroconversion for the flock at 1 day after the 

collection of the last negative sera. CVB will notify licensees and permittees of that 

date. If clinical signs appear in production birds, CVB-IC will set the date of initial 

infection case by case and notify licensees and permittees of the date.

A Veterinary Biologics Investigation (VBI) number is assigned to each outbreak. 

Each firm is required to account for all suspect eggs and chickens it receives. The 

period for suspect eggs should be the 2 weeks prior to the seroconversion date for 

NDV, avian adenovirus, and Salmonella; the 3 weeks prior to the seroconversion date 

for IB and Mycoplasma; and the 4 weeks prior to the seroconversion date for AE, AI, 

LL, REV, and Reo. There is no suspect egg period for LT, IBD, MD, or fowlpox. The 

suspect period for the production birds will be determined case by case.

C. Disposition of Suspect Materials

When a disease outbreak is confirmed within a source flock, licensees and permittees 

should take the following actions:

1. Uninoculated Eggs, Chickens, and Cell Cultures. Discard all suspect eggs, 

chickens, and cell cultures derived from suspect eggs if they have not yet been 

inoculated with production seed.
VETERINARY SERVICES MEMORANDUM NO. 800.65

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2. Inoculated Eggs, Chickens, and Cell Cultures. If already inoculated with 

production seed, discard suspect eggs, chickens, and cell cultures derived from 

suspect eggs, or continue in production, provided the product is appropriately 

tested and the presence of the disqualifying or disease agent cannot be 

demonstrated. (See E below for testing information.)

D. Eggs from Recovered Source Flocks

Licensees and permittees may be permitted to use eggs from a source flock which has 

recovered from a disqualifying disease outbreak for the production of inactivated 

products if the product is appropriately tested and the presence of the disqualifying 

agent cannot be demonstrated. (See E below for testing information.)

E. Testing for Disqualifying or Disease Agents

Appropriate testing depends on the disqualifying or disease agent. CVB will provide a testing 

protocol to licensees and permittees.

1. Test Methods. Testing for disqualifying or disease agents could include, but 

would not be limited to, the following methods:

a. For live products, licensees and permittees should attempt to isolate the 

disqualifying or disease organism from bulk or final container samples of the 

completed product.

b. For killed products, licensees and permittees should attempt to isolate the 

disqualifying or disease organism from samples of the bulk harvest material 

prior to inactivation.

c. For both live and killed products, licensees and permittees should attempt to 

detect seroconversion to the disqualifying or disease agent in chickens 

inoculated with bulk or final container samples of the completed product.

2. For a test result to be considered valid, the appropriate positive and negative 

controls should be used.

3. Reporting Test Results. Licensees or permittees should report results of tests for 

disqualifying or disease agents conducted on bulks or serials of product produced 

from suspect eggs or chickens to CVB-IC on the APHIS Form 2008.

a. Reference VBI number assigned to the disease outbreak in the remarks 

(section 11).

b. Report test data and results in test data section (section 9).
VETERINARY SERVICES MEMORANDUM NO. 800.65

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c. Depending on the test results, mark the appropriate disposition (section 12).

(1) For bulk material, mark “Other” and type “File for Information.”

(2) For final serials in which the test results were satisfactory, mark “Eligible 

for Release.”

(3) For final serials in which test results were reported unsatisfactory, mark 

“Destroyed by Firm” as a confirmation the serial has been destroyed.

d. The CVB will process the APHIS Form 2008 and provide a disposition in 

accordance with VS Memorandum No. 800.53.

e. For serials prepared with bulks that have been deemed acceptable for use, 

note the bulk lot in the remarks (section 11).

VI. IMPLEMENTATION/APPLICABILITY

All Outlines of Production and Special Outlines for products that use embryonated eggs 

or chicken tissue as an ingredient shall conform to this memorandum.